[Lowfer] 1750 meter band skip zone

[w1tag at charter.net]

Paul,

I think your "experts" are having trouble comparing their apples and oranges. 

The daytime groundwave (surface wave) distance depends a lot on ground conductivity. Over seawater, there wouldn't be as much difference between 540 and 185 kHz as there is over land. The worse the ground conductivity (such as here in the northeast U.S.), the greater the advantage at 185 kHz. Even for more normal land, the same ERP at 185 kHz will be much more effective than in the broadcast band. And over the huge 3:1 frequency range of the AM band, the low end is greatly favored over the high. 

To further complicate things, the effective ground conductivity is better in cold weather than warm, leading to increased daytime surface-wave range in winter. I used to copy Lowfer beacons running CW by ear at 300 miles on a cold winter day. 

The real trouble with all of this stuff is comparing ERP's. The Lowfer business has long been known to be slippery! In addition to great differences between antenna efficiencies, some of the transmitters were er...ahhh...less than legal? The secret to many a wild reception report could frequently be described by the alphanumeric sequence "2E26". I won't elaborate.

But, you CANNOT compare a 50 kW mid-AM band signal from a directional array in any useful manner with a 50 microwatt ERP signal at 185 kHz without a LOT of math!
For Lowfers, winter (static quiet and cold) should give 200-300 miles in the daytime with very good setups at each end and the weak-signal techniques we now have. 

John A.